Polyphthalamide thickened greases

ABSTRACT

Lubricating oils thickened to greases with polyphthalamides.

United States Patent Nipe 1 Nov. 20, 1973 [54] POLYPHTHALAMIDE THICKENED 2,710,839 6/1955 Swakon et al. 252/5l.5 A GREASES 2,830,955 4/1958 Dixon 252 51.5 A 2,971,027 2/1961 Holten 252/51.5 A [75] Invent R d p Munster, 3,573,260 3 1971 Morello 260/63 N [73] Assignee: Standard Oil Company, Chicago, Ill. [22] Filed: Sept. 20, 1971 Primary Examiner--Daniel E. Wyman Assistant Examiner-1. Vaughn [211 APPl- 182,166 AttorneyArthur G. Gilkes et al.

[52] US. Cl 252/515 A [58] Field of Search 252/515 A Lubricating oils thickened to greases with polyph- [56] References Cited thalamides UNITED STATES PATENTS 4/1958 Dixon 252/515 A 11 Claims, No Drawings POLYPHTHALAMIDE THICKENED GREASES The invention herein described was made in the course of or under a contract with the Department of the Air Force.

FIELD OF THE INVENTION This invention relates to lubricating grease compositions in which the thickening agent is a polymeric material.

SUMMARYv OF THE INVENTION The lubricant greases of this invention comprise a liq uid lubricating fluid and a thermally stable polyamide substantially free of intramolecular imido linkages.

The present invention is based on the discovery that the herein-described finely-divided solid polymeric ma-. terial, which is chemically unreactive with and insoluble in the lubricating fluid, can be dispersed in the lubricating fluid to form a homogeneous fluid/thickener system that is suitable for use as a lubricant grease.

Polyamides, which are condensation products which contain recurring amide groups as integral parts of the main polymer chains, are a well known class of thermally stable polymeric materials having many uses, especially in fiber, film, coating and plastics industries. The present invention is limited to the use of this known class of polymeric materials as grease-forming thickeners in lubricating oils and fluids. Accordingly, polyamides per se and their preparation do not constitute any part of this invention.

Imido-modified polyamides, wherein the imido linkages are intramolecular, are a well-known sub-class of the general class'of polyamides. For the purposes of this invention, such imido-modified polyamides are excluded. Accordingly, the polyamides embraced by this invention are those polyamides that are substantially free of intramolecular imido linkages.

Except for the limitation that the polyamides are substantially free of intramolecular imido linkages, the

chemical composition and structure of these polymers are not critical with respect to their use as greaseforming thickeners in accordance with this invention. Any combination of aliphatic, aromatic or heterocyclic monomers known in the art for the preparation of thermally stable polyamides can be used. Accordingly, any polyamide substantially free of intramolecular imido linkages that is thermally stable at the temperature of intended use of the grease is suitable for the purposes of this invention.

The polymeric thickener is used in an amount sufficient to thicken the lubricating fluid or form the grease having the desired consistency or penetration. The amount is generally between about 5 and about 50 weight percent, usually between about 8 and about 30 weight percent, of the total composition.

The lubricating fluid component of the greases of this invention can be any normally liquid lubricating oil or fluid of natural or synthetic origin that is normally used in lubricant grease compositions. Illustrative of such oils are the conventional mineral lubricating oils and synthetic lubricating fluids or oils, such as silicone oils, fluorosilicone oils, polyether fluids, polyester fluids, polyfluoro fluids, etc., having viscosities within lubricating oil viscosity range.

The lubricant grease compositions of the present invention can contain, if desired, lubricant additives well known to the art without departing from the scope of the invention. For example, such greases can contain corrosion and/or rust inhibitors, E.P. agents, antioxidants, metal deactivators, stabilizers, anti-wear agents, and the like. The use of such additives and the amounts thereof depend upon the severity of the conditions to which the grease may be subjected.

The polymeric thickeners of this invention are finelydivided thermally stable solid materials which are inert and insoluble in the lubricating fluid. The term thermally stable" means that the thickener does not melt or soften at grease operating temperatures.

The grease compositions are prepared by simply dispersing the solid polymeric thickener, in finely-divided particulate form, such as a powder, in the fluid and then milling the dispersion mixture to the desired grease consistency. Any method of mixing that imparts shearing action may be used. Preferably, the conven' tional grease roll mill is used to form a grease having a stable consistency or penetration. The particle size of the thickener is not critical, but the particles should be as small as possible, since it is well known that the stability of the grease is dependent upon the particle size of the solid thickener. Inasmuch as the polymeric thickener is inert and insoluble in the lubricating fluid, it is to be understood that a plurality of passes through a roll mill and adjustment of fluid content are required to obtain homogenity of the solid thickener/fluid system and effect a stable consistency in the grease.

The CRC L-35 bearing performance test was used to determine the performance of the exemplary grease formulations of this invention as bearing lubricants at elevated operating temperatures. At temperatures below 500 F, the size 204 test bearings were run in high speed test spindles at 10,000 rpm in air, with a 5 pound radial load and a 5 pound axial load on the bearing, for 20 hours out of each 24 hour period until failure. In tests at or above 500 F, the test bearings, under a 50 pound radial load and a 25 pound axial load, were run continuously at the test temperature, until failure. All tests at atmospheric pressure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyamides used as thickeners in the exemplary grease formulations of this invention are:

Polymer A: poly(p-phenylene terephthalamide).

Polymer B: poly(4,4'-diphenylene terephthalamide).

Polymer C: poly(p-phenylene tetrachloroterephthalamide).

Polymer D: poly(N,N'-diphenyl-p-phenylene terephthalamide).

Polymer E: poly(4,4-diphenyl methylene terephthalamide).

Polymer F: poly(4,40'-oxydiphenylene terephthalamide).

Polymer G: poly(terephthaloyl piperazine).

Polymer H: poly(p-phenylene isophthalamide).

Polymer I: poly(m-phenylene terephthalamide).

Polymer J poly(ethylene terepthalamide).

Each of the above polyamides was synthesized by the conventional interfacial condensation method for the preparation of polyamides from non-anhydrideforming dicarboxylic acid and organic diamine reactants. The recovered powdered solids were then incorporated in lubricating fluids to form greases.

EXAMPLE 1 In this example the Dow-Corning silicone polymer lubricating fluid F6-7039 was thickened with the polymers described above. The lubricant grease obtained was then tested as a bearing lubricant. The respective grease formulations, having ASTM D-1403 quartercone penetrations of about 300, and the bearing test results are set forth in Table I:

The liquid lubricating fluid used in forming the greases of this example was Krytox 143AD, a perfluorinated polyether oil derived from hexafluoropropylene oxide. The aforesaid polymers were likewise used as the thickening agents. The greases, having quartercone penetrations of about 300, so formed and the bearing test results are set forth in Table II:

TABLE II Thickener Bearing Test Life (Hours) Polymer at 550 F A 13.3 78 B I6 458 C 19.5 232 C 59 D 17.5 70 E 18.2 280 F 20.8 278 G 33 310 The synthetic lubricating fluids used in the foregoing examples are all commercially available products and are well known in the art.

I claim:

1. The grease composition comprising a lubricating fluid vehicle and a thickening amount of from about 5 to about 50 weight percent of a finely divided solid, thermally stable, interfacial condensation polymer selected from the group consisting of poly(p-phenylene terephthalamide),

poly(4,4'-diphenylene terephthalamide),

poly(4,4'-oxidiphenylene terephthalamide), poly(terephthaloyl piperazine), poly(N,N-diphenyl-p-phenylene terephthalamide poly(p-phenylene tetrachloro terephthalamide), poly(4,4-diphenylmethylene terephthalamide), poly(p-phenylene isophthalamide), poly(m-phenylene terephthalamide) and poly(ethylene terephthalamide); said polymer being insoluble in said fluid.

2. The composition of claim 1 wherein said polymer is poly(p-phenylene terephthalamide).

3. The composition of claim 1 wherein said polymer is poly(4,40-diphenylene terephthalamide).

4. The composition of claim 1 wherein said polymer is poly(4,4'-oxydiphenylene terephthalamide).

5. The composition of claim 1 wherein said polymer is poly(terephthaloyl piperazine).

6. The composition of claim 1 wherein said polymer is poly(N,N'-diphenyl-p-phenylene terephthalamide).

7. The composition of claim 1 wherein said polymer is poly(p-phenylene tetrachloro terephthalamide).

8. The composition of claim 1 wherein said polymer is poly(4,4-diphenylmethylene terephthalamide).

9. The composition of claim 1 wherein said polymer is poly(p-phenylene isopthalamide).

10. The composition of claim 1 wherein said polymer is poly(m-phenylene terephthalamide).

11. The composition of claim 1 wherein said polymer is poly(ethylene terephthalamide). II F P0405? UNIT ED STATES PAIEN'L OFFECE T! T) a? (5/69) I r T1 h r CERTlFiCAIiL 011 o wcrloN Dated Nmlemhen 1913 Patent No. 3,773.666

Invenc fl RICHARD NLNIPE that error appears in the above-identified peten't It is certified y corrected as shown below: j

and that said Letters Patent are hereb C01. 2, line 56, for "4,40'" rad; 4,4

C01. 3, 1 ine 35, delete the first "C"' under the Polymer heading in Table 11. l g 001. 4,'. 1 ine '23,'for "4,401" reed" 4,4'

' Signed and sealed this- 16th day of April 19-71;.

'(SEAL).

Attest:

o mR sz-mL-L' DANN Commissioner of Patents EPI'JARD M {FLETCHER ,JR

Attesting Officer 

2. The composition of claim 1 wherein said polymer is poly(p-phenylene terephthalamide).
 3. The composition of claim 1 wherein said polymer is poly(4, 40''-diphenylene terephthalamide).
 4. The composition of claim 1 wherein said polymer is poly(4,4''-oxydiphenylene terephthalamide).
 5. The composition of claim 1 wherein said polymer is poly(terephthaloyl piperazine).
 6. The composition of claim 1 wherein said polymer is poly(N,N''-diphenyl-p-phenylene terephthalamide).
 7. The composition of claim 1 wherein said polymer is poly(p-phenylene tetrachloro terephthalamide).
 8. The composition of claim 1 wherein said polymer is poly(4,4''-diphenylmethylene terephthalamide).
 9. The composition of claim 1 wherein said polymer is poly(p-phenylene isopthalamide).
 10. The composition of claim 1 wherein said polymer is poly(m-phenylene terephthalamide).
 11. The composition of claim 1 wherein said polymer is poly(ethylene terephthalamide). 